Conventionally, a stator of a rotating electric machine includes a cylindrical stator core and stator coils. The cylindrical stator core has a plurality of teeth (magnetic poles) that are radially arranged side by side and project in a radially inward direction and a plurality of slots that open between the teeth. The stator coils are assembled with the stator core by accommodating coil side parts into those slots. A method for fabricating stator coils in advance separately from a stator core and assembling the stator coils with each of the slots of the stator core is known as a stator coil assembling method.
For example, the following method has been proposed as a stator manufacturing method (see, for example, JP2007-166850A and JP2011-229285A). The method uses an insertion tool in which a plurality of holding grooves corresponding to slots of a stator core are formed on an outer periphery so that a pair of side parts of each of a plurality of coils wound in advance are successively inserted into two holding grooves separated by a predetermined width. The method also arranges the plurality of coils along the outer periphery of the insertion tool and inserts the insertion tool that the plurality of coils wound thereon into the inner periphery of the stator core so that each holding groove is positioned to be aligned with the corresponding slot of the stator core. Subsequently, the method inserts a plurality of plate-like pushers that narrow in width toward the tips into the corresponding holding grooves from the tips of the plate-like pushers. The method also pushes out the pair of side parts of each coil inserted into the holding grooves toward a radially outer side and inserts the side parts into the corresponding slots of the stator core.
In this stator manufacturing method, the side parts of the coils wound on the insertion tool are pushed out toward the radially outer side and inserted into the slots. Thus, it is possible to reduce damage to wire materials constituting the coils by preventing considerable deformation of the coils. Here, in the stator coil inserted into each slot of the stator core, parts accommodated into the slots serve as coil side parts and remaining coil parts projecting from end surfaces of the stator core without being inserted into the slots serve as coil end parts.